Think Globally, Act Personally

Fossil fuel interests exert inordinate control over the world’s economies and politics, so much of the transition will fall to individuals. Transportation, representing 27% of U.S. energy consumption, with roughly half of that going to light duty vehicles,¹ offers some of the lowest hanging fruit. Four steps can help propel us forward:

1. Reduce demand for motorized travel, by replacing some motion with forethought. Examples would include telecommuting, trip consolidation, or moving closer to one’s workplace.
2. Use vehicles more productively, by better matching vehicle size to payload size. Downsizing to a smaller vehicle is one way to accomplish this, carpooling is another.
3. Electrify vehicle powertrains, to the maximum extent allowed by the vehicles’ use cases.
4. Generate electricity renewably.

It’s important to rebut the mistaken argument that we shouldn’t buy electric vehicles (EVs, step 3) before we fully green the grid (step 4). In fact, each step represents immediate progress, today, even if taken in isolation. For details, see the Union of Concerned Scientists’ excellent analysis.² However, to the extent that there might be a correct order, it’s as shown. Conservation enables technology. Steps 1 and 2 are pure conservation steps. Step 3, vehicle electrification, incorporates both technology and significant conservation. Step 4 is purely technological.

None of these actions require permission. Neither OPEC, nor the president, nor anyone else has veto power. The only barrier for many people is sufficient confidence in their ability to approach steps 3 and 4 wisely.

The Difference Between Energy and Power

Though often conflated, energy and power are two distinct things. Energy is the ability to do work. Engineers and scientists have a very specific, mathematical definition of work, but it’s irrelevant here. Suffice it to say that, if doing something manually could cause you to sweat, there’s work involved.

Power is the rate at which energy is transferred or, stated another way, the speed at which work is done. If we think of energy as a substance, like water, then power is the flow rate, how fast we’re pumping the water.

Work and energy have dimensions of force times distance: Newton-meters (Nm) in SI units. To distinguish energy from torque, we call a Nm of energy a Joule (J). Power is the amount of energy transferred divided by the time it took to transfer it, Joules per second (J/s), which we call watts (W).

We distinguish size ranges using prefixes. A typical cell phone charger transfers electrical energy at a rate of about 5 W. A kilowatt (kW) is 1000 W; a lawnmower, running at full throttle, does work at a rate of about 3 kW (4 horsepower). A megawatt (MW) is 1000 kW; a railroad locomotive, running at full throttle, does work at about 3 MW. A gigawatt (GW) is 1000 MW; a modern nuclear reactor generates electricity at about 1 GW.

Since power is energy divided by time, energy is power multiplied by time: one Joule is equal to one watt-second. Measuring electrical energy is hard, but measuring electrical power is fairly easy, so utilities measure power (kW), multiply by the time the power was drawn (hours, h), add it all up at the end of the month, and bill customers for energy in kilowatt-hours (kWh). Depending on the size of the numbers, we might also express energy in watt-hours (Wh).

What does the Difference Make? (PV Edition)

People buy photovoltaic (PV) systems to produce energy (kWh). They are often sized in terms of power (W, kW). For comparison’s sake, it can be useful to think about the price of PV systems in $/watt. PV output varies with the sun’s brightness. Panels are rated by their electrical output under “peak” sun, defined as 1000 watts of light power per square meter. Actual light input depends on location, weather, and time of day and year. Additionally PV panel orientation, comprising tilt (angle above the horizontal) and azimuth (compass direction the panel faces), is also important. Some panels are on fixed mounts, others on trackers which vary the orientation to follow the sun.

Considering these factors, the amount of sunshine that hits the panel during a given time period can be expressed in “peak sun hours,” the number of hours of full noontime sun that would result in the same amount of light hitting the panel.

The National Laboratory of the Rockies (formerly NREL) has compiled extensive data on the solar resource across the United States, and programmed them into a calculator incorporating panel type and orientation to provide a month-by-month estimate of PV output in any given location. This calculator, called PVWatts, is online, and quite intuitive to use.³

2015 Chevy Spark EV listing from fueleconomy.gov. © Oak Ridge National Laboratory

To estimate peak sun hours, the PVWatts user can input data for a one kW system. The resulting energy output in kWh is numerically equal to the number of full sun hours for that location.

What Difference does the Difference Make? (EV Edition)

The power of an EV’s motor (or an internal combustion vehicle’s engine) directly impacts its dynamic performance: acceleration, top speed, gradability (the combination of speed and slope the vehicle can maintain while climbing), and towing capacity. When charging, the electrical power input (usually stated in kW) and the vehicle’s energy intensity (measured for our purposes in Wh/mile) combine to determine charging speed, the miles of range replenished for each hour spent charging.

Energy intensity can be found on the Environmental Protection Agency (EPA) fuel economy website.4 However, EPA’s numbers require some massage. Mileage values for the Combined, City, and Highway cycles of the standard fuel economy test are shown in “equivalent miles per gallon.” MPGe relates all energy consumption, regardless of fuel, to the amount of energy in standard unleaded gasoline, 33.7 kWh per gallon. To turn mileage in MPGe into the corresponding energy intensity in Wh/mi, divide it into 33,700. Conversely, we can turn energy intensity in Wh/mi into MPGe by dividing it into 33,700.

EPA also provides Combined cycle energy intensity numbers in kWh/100 miles. To convert these into Wh/mi, simply multiply by 10. Combined cycle energy intensity for 2025-26 EVs lies between 230 Wh/mi (146 MPGe) and 720 Wh/mi (47 MPGe). Unlike combustion vehicles, City cycle consumption is lower than Highway for EVs. Coupled with the energy intensity, battery energy capacity (typically expressed in kWh) determines range, the distance the vehicle can travel on a charge.

The Final Countdown

Finding the PV capacity needed to charge the EV requires three data points: vehicle energy intensity (Wh/mi), annual vehicle miles traveled, and annual full sun hours at the site. Multiply energy intensity by vehicle miles traveled, then divide by full sun hours to get the amount of PV required (in W).

Using 1,400 full sun hours per year (the ten year average measured at my family’s home in Asheville, NC), 185 Wh/mi (the five year average for our Chevy Spark EV), and 6,000 mi/yr (our typical usage of the Spark), we see that the Spark consumed the output of 793 W, 13 percent of our 6 kW PV system.

Though these are real world numbers, this result is anomalously low, shown here to illustrate the danger of relying on anecdotal data. My wife and I are experienced EV drivers; our driving style tends to maximize range. Asheville is a very compact town, which minimizes the total miles traveled and maximizes the city portion of those miles. And the Spark was one of two EVs in our garage; the other one took the road trips.

EPA rates the Spark EV at 280 Wh/mi (119 MPGe) on the Combined cycle. The average American drives about 15,000 mi/yr. Using these numbers, the Spark would require the output of 3,000 W of PV, half of our 6 kW system. Driving style and distance traveled both matter. EV owners who already know their actual consumption can use that number in the calculation. The best approach for everyone else is to use the EPA Combined cycle number, because the EPA test is highly repeatable, and the Combined cycle is the best estimate of “average” U.S. driving. But nobody is actually average; we’re all above or below average. If you have a heavy right foot, or if you’d like to build a little cushion into your calculation, using the EPA Highway figure will provide a more conservative estimate.

Why Not Put the PV on the EV?

As the owner of two cars with license plates that misspell “solar car,” I get frequent pushback about the lack of solar panels on either. My panels are on the roof of my house, where they’re always properly oriented and never shaded; and on the grid, where there’s always a useful place for their output to go, even when the batteries are full. They add no weight or aerodynamic drag to the cars, and are unaffected by the brutal shock and vibration cars endure. They’re precisely where they belong.

Though permanently mounting PV

on an EV is unlikely to make sense, changes to net metering protocols, driven by fossil fuel shills in state legislatures, may change the cost equation enough to make an off-grid combination of PV and EV attractive. Declining hardware costs have already made EVs an effective source of backup power. Whether with auto manufacturer-approved systems or with simple homebrewed inverter setups, several of my neighbors put their EVs to useful (indeed, lifesaving) service during 2024’s Hurricane Helene. We’ll see a lot more of this V2L (vehicle-to-load) activity in the future. But that’s a topic for another article.

Low Hanging Fruit

Driving on sunshine is cleaner, quieter, and more pleasant than burning dead dinosaurs. It can save a lot of cash and insulate drivers from inflation. It keeps money in the community, and out of the hands of petrostate despots. And it’s ripe for the picking.

About the Author
Automotive engineer and ASES Life Member Dave Erb has developed vehicles using gasoline, diesel, biodiesel, alcohol, natural gas, electric, and hybrid electric powertrains. He and his wife live in a beyond net zero house, and haven’t bought gas since 2019.

Sources:

1. tinyurl.com/eia-transportation-energy
2. tinyurl.com/ucs-blog-drive-electric
3. https://pvwatts.nrel.gov/pvwatts.php
4. https://fueleconomy.gov

“I’d put my money on the sun and solar energy. What a source of power! I hope we don’t have to wait until oil and coal run out before we tackle that.”
– Thomas Edison

Solar Light to Electricity Conversion

The sunlight that hits a square foot of any surface carries 127 watts of energy. The ideal solar panel would convert 100% of this energy into electricity.

The history of commercial use of solar energy began in the mid-20th century when Bell Labs introduced the first practical silicon photovoltaic (PV) cell, boasting a then-revolutionary 6% efficiency. By the late 1950s, companies like Hoffman Electronics had pushed efficiencies to 14%, sparking commercial interest and laying the groundwork for the solar industry’s future. In 2025, solar panel efficiency continued to break new ground – LONGi launched a solar panel with a remarkable 33% efficiency in their large-area (260.9 cm²) crystalline silicon-perovskite two-terminal tandem solar cell. These efficiency gains not only demonstrate the technical feasibility of solar power but also ignite commercial and governmental interest, setting the stage for the industry’s further development.

From Pioneering Innovation to Global Expansion

The 1970s energy crisis marked a turning point. Governments and corporations, eager for alternatives to fossil fuels, accelerated solar R&D. ARCO Solar emerged as a trailblazer, becoming the first company to produce one megawatt of PV modules in a single year by 1980. Meanwhile, Japanese firms such as Sharp and Kyocera established themselves as global leaders, driving advancements in efficiency and reliability.

The 1990s saw a surge in investment, with brands like SolarWorld facilitating the adoption of crystalline silicon panels across Europe. In the United States, initiatives like the “One Million Solar Roofs” program further fueled demand for commercial solar solutions.

ARCO solar panel. © Museum of Solar

Market Shifts and the Fall of Industry Icons

The 2000s ushered in a new era of innovation, with thin-film technologies and high-efficiency modules from companies like First Solar and SunPower. This period also saw the rise of Chinese manufacturing, which dramatically lowered costs and intensified global competition.

By the 2010s, many established brands struggled to adapt. BP Solar, a committed player since the 1980s, exited the market in 2011. Solyndra, once celebrated for its unique cylindrical panels, filed for bankruptcy the same year amid unsustainable production costs. Other notable departures included Evergreen Solar, Schott Solar, and SolarWorld—each leaving a legacy of technological advancement and market expansion.

Remembering the Brands that Shaped the Industry

Despite their market exits, these discontinued brands made significant contributions to the solar industry. BP Solar was instrumental in advancing crystalline silicon technology and helped establish early commercial markets. Solyndra’s innovative cylindrical solar panels, though commercially unsuccessful, demonstrated the potential for alternative PV designs. Evergreen Solar contributed to cost reduction initiatives and manufacturing process improvements.

Ad for Bell Telephone System.

The list of discontinued solar panel brands is long and storied, featuring names such as Uni-Solar, HelioVolt, and Abound Solar, etc. Their experiences offer valuable lessons on the importance of innovation, adaptability, and strategic foresight in a rapidly changing market. Bluewater, a leading USA second-life solar equipment player, posted the full list of discontinued solar panel brands and their years in service.¹

The exit of these major players created both challenges and opportunities in the solar industry.

The After-Market Opportunity: A New Chapter for Solar

As more legacy panels reach the end of their service lives, the need to replace discontinued brands supports the after-market for solar components. Many solar consumers will be looking to source older components to match their array.

According to a recent Wood Mackenzie report, the U.S.now boasts north of 248 GW of installed solar PV capacity,² with over half a billion solar panels currently in operation.

As more panels approach the end of their 25–30 year lifespan, or are proactively replaced as part of preventive maintenance plans, the demand for solar panel replacements is growing.

In 2025 alone, the U.S. market saw tens of millions of panels replaced, and with the total installed solar capacity having grown nearly 100x since 2010, the need for replacements is expected to double each year for the next decade. Custom-sourcing matching solar panels increases utilization of idle equipment, and allows the continued performance of existing solar installations without a major overhaul.

Full list of discontinued solar panel brands: bluewaterbattery.com/discontinued-solar.

About the Author
Max Khabur is a Director of Marketing
at Bluewater, one of the U.S. leading operators in the second-life solar equipment and battery market. Formerly Max led marketing at OneCharge Lithium Batteries, and was elected Chairman of the Advanced Energy Council, representing a group of companies – members of the MHI.org (Materials Handling Industry) Association.

Sources:

1. https://www.bluewaterbattery.com/discontinued-solar
2. “US Solar Market Insight: 2024 year in review” published by Solar Energy Industries Association (SEIA).

But on many commercial roofs, and especially on flat rooftops, the real constraint is not the sun. It is space.

When roof area is limited, the question becomes: What layout lets you install the most space-efficient solar capacity within budget on the available area? In those scenarios, an east–west (E–W) layout can outperform a south-facing layout. The South layout may be “better positioned”, but the E-W allows the installation of more panels in the same area.

This article walks through when an E-W configuration makes sense, using a straightforward roof example and five case studies across the U.S.

A Quick Clarification: What We are Comparing

Before the numbers, it helps to define what “better positioned” means:

• South-facing fixed tilt at optimal inclination often maximizes energy per panel.
• E-W at low fixed tilt often maximizes power per available area.

The Two Conditions where East–West Shines

East–West is not a replacement for south-facing arrays in every situation. The advantage tends to show up when both conditions apply:

• You are working on a flat surface. This includes flat roofs (such as malls, warehouses, office buildings, apartments, and houses), flat canopies with space constraints, and potentially floating PV platforms, such as those on ponds or reservoirs.
• The tilt angle is low: from 5° to 10.° Low-tilt arrays are commonly used on flat roofs because they can reduce wind uplift forces and minimize row-to-row shading.

Low tilt is common on flat roofs for practical reasons:

• It reduces the uplift load and helps manage wind-related structural requirements.
• It can reduce row-to-row shading constraints because the array sits lower.
• It can simplify roof loading strategies when using ballast systems.

When those two conditions are present, east-west layouts often allow tighter packing, meaning a higher power density. Also, on a space-limited roof, higher power density can translate into stronger project economics.

A Simple Roof Example (4,290 sqf)

To illustrate this trade-off, consider a flat surface measuring 4,290 square feet (sq ft) with the goal of installing as much solar capacity as is practical.

Option A is a conventional design approach that would use a south-facing ballast-mounted system. Using 450-watt modules at a 10° tilt, this surface can accommodate 120 panels, resulting in a 54 kW DC system.

Option B is an E-W configuration using the same 450-watt modules. With an 8° tilt (the same angle used by the same manufacturer for the South example), the same surface can fit 152 panels, for a total of 68.4 kW DC.

What Changed?

The roof did not get bigger. The type of module did not change. What changed is the layout efficiency.

In this example, the east–west configuration increases installed capacity from 54.0 kW to 68.4 kW, a 27% increase in capacity on the same footprint. That is the core advantage: more watts installed per square foot, which will generate more energy.

What Does that Mean for Energy Production?

To understand how this plays out, five case studies were evaluated using NREL’s PVWatts tool, assuming a 0.5% annual module degradation rate. The locations were chosen to represent a range of U.S. climates:

• Orlando, Florida
• Bakersfield, California
• Malta, New York
• Seattle, Washington
• Lincoln, Nebraska

As expected, the east–west systems produce more energy in every location, not because they are more efficient per panel, but because they are larger systems on the same roof. Of course, if you can install the same amount of PV modules facing south, you will get higher energy generation than the E-W, but can you install more?

The more important question, however, is whether that additional production justifies the cost.

Installed Cost: More Capacity Does Not Always Mean Higher Cost

Estimated installed costs were calculated for each system, accounting for typical regional labor rates and site-specific structural requirements.

Structural costs vary by location. High-wind regions, such as Orlando (design wind speeds up to 137 mph), and heavy-snow areas, such as Malta, New York which can reach up to 76 pounds per square feet (psf), increase racking and ballast requirements. These factors affect both layouts, though E-W systems can sometimes distribute loads more efficiently.

Option A (left): South-facing ballast system, tilt angle 10,° 120x450W PV modules. Option B (right): E-W facing ballast system, tilt angle 8,° 152x450W PV modules. © Baker Makarem

The electrical scope, often the source of unforeseen challenges during construction, was assumed to be similar for both cases.

A Helpful Metric: Cost per Installed kW peak ($/ kWp)

This metric helps answer: How much solar capacity do you get for each dollar invested?

Across these five cases, the east–west configuration averages about 16% lower cost per installed kilowatt than the south-facing layout, with some locations showing differences as low as 23%.

For example, with a $20k budget in Seattle, a south-facing layout would allow for up to 11.69 kWp of installed capacity, producing about 11,228 kWh in the first year.

With the same budget using an east–west configuration, you could install up to 13.69 kWp of PV, with an estimated annual production of 12,074 kWh.

Payback and ROI: Where the Comparison Becomes Real

Payback Period. Payback refers to how long it takes for the system’s savings (from electricity generated) to recover the initial investment.

The analysis for the city of Orlando assumes an electricity price of $0.11 per kWh and a 6% annual increase in electricity rates. The east–west system reaches payback sooner than the south-facing system, reflecting its higher production and lower cost per kilowatt.

Payback time in years, Orlando, FL. © Baker Makarem

A shorter payback also leaves more financial margin over the system’s life to cover capital expenses, such as inverter replacements.

Return on Investment (ROI). This is another metric to consider, which measures net savings vs. investment. Across the 5 scenarios, the ROI ranged between 130% to 252%. These values can vary depending on expenses during the 20-year estimated lifespan of the system.

The message is consistent: in these examples, east–west layouts deliver stronger ROI because they install more capacity per roof area and typically do so at a lower cost per kilowatt, with higher energy production, compared to what can be installed facing south.

A Few Important Considerations

These exercises were intentionally simplified to focus on layout trade-offs. Several real-world factors can change outcomes:

• Savings were calculated without rebates or incentives. Which is, in some aspect, a better perspective, since the Federal Solar Investment Tax Credit (ITC) is no longer available.
• For commercial projects, depreciation treatment can shorten payback periods and increase ROI.
• Operations and maintenance costs were not modelled in detail. While these systems will incur maintenance expenses over a 20-year lifespan, the overall profitability remains strong.
• It is also worth noting that east–west arrays often produce a broader daily generation profile, with more output in the morning and late afternoon. In markets with time-of-use pricing and demand charges, this flatter production curve can add additional value.

Takeaways

East–west solar configurations are not a replacement for south-facing systems, but they can be more profitable in the right scenarios.

They tend to perform best when:

• The surface is flat (common in commercial buildings)
• The design uses low tilt angles (5° to 10°)
• Roof area is the primary concern

These conditions are common in commercial buildings, warehouses, and increasingly in floating PV systems. As floating solar continues to develop, east–west layouts may play an important role in maximizing energy output per available surface.

Sometimes, the best solar design is not about chasing the perfect angle, but about making the most of the space you have.

About the Authors
Baker Makarem is a Mechanical Engineer and NABCEP-certified ESIP, PVIP, and PVSI. He is the founder of Bakertech, a company specialized in the photovoltaic (PV) and energy storage systems (ESS) industry. He has been in the renewable energy field since 2017.

Carla Monzer previously worked as a marketing consultant in a global market research firm providing consumer, industry, and market intelligence. She is currently a PhD student in Marketing at the University of South Florida. Her research interests focus on sustainability, with particular attention to renewable energy and its interaction with consumer behavior.

Necessity, as the saying goes, is the mother of invention. In the solar supply chain, the shift toward more localized production has proven transformative – driving value creation, strengthening energy security, increasing public acceptance of the energy transition, and improving sustainability outcomes.

While the initial push toward local manufacturing was largely driven by an urgent need, the benefits have since become increasingly compelling, particularly in reducing carbon emissions and fostering a more environmentally-responsible solar supply chain.

In today’s fast-moving solar industry, the supply disruptions caused by the COVID-19 pandemic may feel like a distant memory. Yet the repercussions of that period continue to reverberate. In early 2021, soaring shipping demand collided with constrained logistics capacity, causing shipping container costs to surge, particularly on long-distance routes.

At the time, UN Development and Trade reported that shipping costs between Asia and North America’s East Coast had increased by more than 60%, while costs between China and South America rose by an extraordinary 440%. One lasting outcome of this disruption has been a renewed focus on supply-chain security and the near- or on-shoring of component manufacturing. These efforts have been reinforced by broader discussions around the economic and strategic value of domestic solar-component production, as well as by policy initiatives designed to incentivize in-country manufacturing – most notably the Biden Administration’s Inflation Reduction Act.

Local Production 2.0

Solar supply routes remain exposed to a range of risks. In its Energy Technology Perspectives 2024 report, the International Energy Agency (IEA) highlighted the solar and clean energy sector’s reliance on “maritime chokepoints,” such as the piracy-prone Strait of Malacca. According to the IEA, roughly 50% of clean technology shipments pass through these potentially troubled waters.

Building on its heritage in tracker supply and long familiar with the logistical challenges of transporting heavy steel components, Nextpower has been at the forefront of supply-chain localization. In less than three years, Nextpower transformed its U.S. supply chain and now works with more than 40 suppliers across North America – executing projects cost-effectively, with reduced supply-chain risk and 100% domestic content (see Table 1).

As 2026 dawns, Nextpower is sourcing components from more than 100 manufacturing sites in more than 45 countries.

Standing up new manufacturing facilities or adding production lines is an enormous corporate effort – particularly when maintaining rigorous quality standards and keeping costs under control. Even more challenging is doing so on an accelerated timeline, as is often required to meet domestic-content requirements.

But this geographically diversified manufacturing footprint continues to deliver clear supply chain advantages. Manufacturing facilities established earlier this decade have demonstrated their ability to deliver meaningful value for solar project developers, local communities, and the environment alike.

Job Creation

The creation of new employment opportunities in a future-focused industry is a major benefit of establishing local production. The idea of a “just energy transition,” in which climate action goes hand in hand with efforts to address economic inequality, originated within the North American labor movement and is now widely embraced. It has even been embedded in the language of the landmark 2015 Paris Agreement. By creating jobs across the value chain, the benefits of the energy transition are shared more broadly across society.

In 2024, Nextpower commissioned an independent study to quantify the impact of its local job creation efforts across North America. The study found that more than 7,780 jobs had been created, including 2,470 direct jobs, 2,350 indirect jobs, and 2,960 induced jobs – spanning manufacturing, fabrication, engineering, construction, research and development, and trucking and transportation.

These figures help quantify the substantial positive impact that solar project development and local production can deliver – yet the most enduring benefits cannot be captured by statistics alone.

Unlike the fossil fuel–dominated power system, which was built around a centralized “hub-and-spoke” model, the energy transition is giving rise to a more distributed, network-based electricity system. Clean energy generation is increasingly spread throughout the grid and often located closer to peri-urban and rural communities.

As communities come into closer contact with solar, wind, energy storage, and transmission projects, tensions can arise, sometimes slowing permitting processes or halting development altogether. When project development is accompanied by local job creation and economic participation, however, community acceptance is more readily achieved, helping to align local interests with the broader goals of the energy transition.

Enhanced Sustainability

While job creation and economic value are important outcomes of local production, its greatest impact is systemic – reshaping the sustainability profile of the solar supply chain itself. By way of context, global solar installations easily surpassed 600 GW in 2025, up from less than 60 GW just a decade ago. With solar now deploying at this massive scale, the sustainability of its supply chain has become as critical as the clean energy it delivers.

One clear example is steel production. In the United States, steel manufacturing is via Electric Arc Furnace (EAF) technology, which delivers significant emissions reductions compared with traditional Blast Furnace–Basic Oxygen Furnace (BF-BOF) methods. While BF-BOF steel production typically emits around 2.5 tons of CO₂ per ton of steel, EAF production generates only a fraction of that, approximately 0.8 tons. EAF processes also makes use of recycled steel as a feedstock – another environmental win.

Validation and Credentials

Translating these sustainability gains into products was an obvious next step. In April 2024, Nextpower introduced its NX Horizon Low Carbon Tracker (LCT) product to the market – a global first for the industry. Based on third-party verification, the solution delivers up to a 42% reduction in embedded carbon, compared with conventional alternatives.

For its flagship NX Horizon trackers, Nextpower is also raising the bar on sustainability. In 2025, the company became the first tracker manufacturer to develop an Environmental Product Declaration (EPD) – essentially a verified sustainability datasheet. While EPDs are commonplace in mature industries such as automotive, their adoption in solar represents an important step forward. An EPD enhances transparency and establishes a clear sustainability baseline from which continuous improvements can be measured.

UMX line worker at Unimacts, Las Vegas, NV. © Nextpower

Accurately measuring and transparently reporting greenhouse gas emissions across solar tracker production and supply chains is critically important. According to Nextpower’s internal analysis, while PV modules – including cells, glass, and other materials – remain the largest source of embedded carbon in a utility-scale solar project at 43%, trackers are not far behind, accounting for 21%. By deploying NX Horizon LCT, that share can be slashed by almost half, to just 11%.

Another long-overlooked contributor to project emissions also warrants closer attention: aluminum module frames. Although slender, aluminum frames are responsible for an outsized 25% of a project’s embedded carbon. Here, too, meaningful progress can be made.

By replacing energy-intensive aluminum with steel frames, frame-related emissions can be reduced by 80% to 90% depending on the raw material source. Recognizing both this emissions advantage and the added structural robustness steel offers for today’s large-format modules, Nextpower acquired steel-frame developer Origami Solar in September 2025. The company is now working with project developers to bring this innovative approach into the industry mainstream.

Taken together, the combination of steel module frames and NX Horizon LCR enables utility-scale solar developers to reduce overall project greenhouse gas emissions by up to 32%, presenting a compelling and practical pathway to deeper decarbonization. Looking further ahead, the increasing adoption of EAF steel production opens the door to green steel in solar projects. Strategic partnerships between solar manufacturers and emerging green steel producers could therefore unlock a fully sustainable, locally anchored supply chain.

Cost and the Future

Raising the bar on sustainable materials and processes inevitably brings added complexity and cost. Similarly, local production is rarely, at least initially, the lowest-cost option. Over time, however, experience, scale, and the learning curve that has long benefited the solar industry can drive costs down. Encouragingly, a future in which local, sustainable production is also cost-competitive is well within reach.

There is little doubt that the solar industry is entering a new era – one defined by both tremendous opportunity and shared responsibility to both communities and the environment. A localized supply chain with sustainability at its core offers a clear path forward: enabling decarbonization that is cost-effective, equitable, and as environmentally responsible as possible.

About the Author
Yves Figuerola is SVP of Supply Chain and Sustainability at Nextpower. With over 15 years of experience in strategic sourcing, logistics, and operations leadership across multiple continents,
he specializes in building resilient, cost-efficient supply chains for large-scale solar manufacturing. Yves holds a Master of Science in Industrial & Mechanical Engineering from Arts et Métiers ParisTech and a Master of Science in Industrial Organisation & Supply Management from Universidad Carlos III de Madrid.

Electrical Vehicle (EV) adoption in the United States has grown rapidly. EVs reached more than 1.2 million sales in 2024, and represented about 7.5% of light-duty vehicle sales in the second quarter of 2025, according to the U.S. Energy Information Administration (EIA).¹

According to a recent Edmunds article,² used EVs are selling faster than used internal combustion engine (ICE) vehicles, at approximately 34 days to sell, compared with used ICE automobiles, which are averaging 43 days.

However, now that the U.S. government is no longer providing tax incentives, the number of new EV sales is already declining in 2026 (though there is no sign of decline in other countries).

Typical V2H configuration with Solar and ESS. © Baker Makarem

As EV battery capacities increase, many homeowners are beginning to see their vehicles not only as transportation, but also as a potentially substantial backup power resource.

Before looking at how V2H works, I will briefly clarify the different types of electric vehicles:

• Battery-electric vehicles (BEVs) run entirely on electricity and are charged by the grid or a solar-powered home system.
• Hybrid electric vehicles (HEVs) combine a gasoline engine with a smaller battery that is charged internally, either by regenerative braking or the alternator.
• Plug-in hybrid electric vehicles (PHEVs) are a mix of both BEV and HEV and have larger batteries than the HEV, and can also be charged from an external source.

Almost in parallel with EV growth, more homeowners are installing rooftop photovoltaic (PV) systems. One study found that roughly one in four EV owners also own solar,³ which is a natural pairing, since both technologies allow households to reduce emissions, cost, and gain greater energy independence.

How Does Vehicle-to-Home Actually Work?

Vehicle-to-home relies on bidirectional charging, as opposed to a typical EV charging setup, in which electricity flows only one way, from the home or grid into the vehicle.

A bidirectional charger, however, allows electricity to move in either direction. When needed, or also when electricity rates are high, the EV battery can discharge energy back into the home or back to the grid to be sold.

Several major automakers now support or plan to support bidirectional capability in the U.S. market. These include GM, with several EV models such as Silverado, Equinox, Bolt, Hummer, and Cadillac; Ford with the F150 Lightning, Tesla with the Cybertruck, Hyundai with their IONIQ family, and many others. There will also soon be ways to retrofit existing EVs for this purpose.

The functionality depends not only on the vehicle, but also on the charger, inverter, and home electrical configuration. In all cases, the home must include means to safely isolate the house from the utility grid during backup operation, so as not to harm linemen during an outage. Here’s how it works: in normal grid operation, the EV is charged via the grid. In an outage, the microgrid interconnection device (MID) switches to backup mode, powering only what is in the backup section (the homeowner can choose how much of the house needs to be backed up). The dark start battery (DSB) powers the components to keep communication, while waiting for the EV to plug in and the customer to initiate the backup mode.

Put simply, the EV battery serves as a temporary home power source, similar to a stationary home battery. Because EV batteries are often much larger than typical residential storage systems, one fully charged vehicle can supply a home for many hours, sometimes even multiple days, depending on usage and the support of additional sources such as a rooftop solar system.

There is also another advantage: using the battery to sell electricity back to the grid. Homeowners who live in a region where the utility charges time-of-use (TOU) prices, the homeowner can fill up at night when there is less demand for electricity, or in some places, such as California, where there is an abundance of solar keeping prices down, and then send (and sell) power back to the grid when demand is high and more expensive.

Why V2H Matters for Resilience

Power outages are becoming more frequent in many parts of the country due to severe storms, grid congestion, and wildfire-related shutoffs. Nationally, the average outage lasts about 11 hours,⁴ although the duration can be much higher in certain states and during extreme weather events.

There are states such as South Carolina where the average duration of interruption is greater than 50 hours, and the number of interruptions is close to two and a half days.

Traditionally, homeowners seeking backup power have relied on diesel or gasoline generators. More recently, stationary lithium-ion storage systems alone or paired with rooftop solar have become popular. V2H adds a new option: using the battery you already drive.

For homeowners who already own an EV, V2H could:

• reduce or eliminate the need for generators
• provide quiet, clean backup power
• complement rooftop solar
• improve household energy independence

U.S. Energy Information Administration, Average annual total electric power interruptions by state (2024). retrieved from EIA,In Brief Analysis: Hurricanes in 2024 led to the most hours without power in the United States in 10 years; https://www.eia.gov/todayinenergy/detail.php?id=66744, January 5, 2026. © eia

And because EV batteries range widely in size, from about 60 kWh in many BEVs to even higher capacities in some models, they can store significantly more energy than the average stationary home battery. Also, of course, it does not have to be fixed to one place. If the battery runs low, the homeowner has the option to drive to a nearby functioning supercharger, leaving the house without power for only a short time.

Additionally, and from an emissions standpoint, battery-electric vehicles produce roughly 70–80% fewer lifetime CO₂ emissions than conventional gasoline vehicles, depending on the regional electricity mix. Plug-in hybrids typically provide moderate reductions as well. HEV is approximately 45% less, and a PHEV is 63% less.⁵

U.S. Bureau of Labor Statistics, Average Price: Electricity per Kilowatt-Hour in U.S. City Average [APU000072610], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/APU000072610, January 5, 2026. © FRED

Facts and Studies: What Research Says About Costs

Readers often ask: How much does owning an electric vehicle really cost, and how does V2H change the equation? When compared with fueling and maintaining a conventional gasoline vehicle, the difference is substantial. So, while EV drivers do buy more electricity, their total fuel, maintenance, and time spent is significantly lower.

A simple real-world comparison illustrates this further. One road test reported that an electric pickup truck traveled 400 miles using 204 kWh of stored energy.⁶ Using the U.S. average residential electricity rate of $0.188 per kWh,⁷ that full charge would cost: 204 kWh × $0.188/kWh = $38.35.

It is important to note that the average price of electricity has increased from 2020 to 2025 by approximately 40%, and is expected to continue to rise.

The gasoline version of the same truck has a 24-gallon tank. At an average retail gasoline price of $3.2288 per gallon, filling the tank would cost $77.47.

There are additional cost savings associated with electric cars. EVs do not need oil changes, and due to regenerative braking, where the motor slows the car, rather than brake pads only, EVs need many fewer brake replacements. Additionally, EV motors have between 20 and 50 moving parts, versus over 1,000 for ICE cars. With a lot fewer parts, there are a lot fewer, and costly, things to go wrong.

Here it can be seen that the average price of gas has increased from 2020 to 2025 by approximately 75%.

A recent peer-reviewed study examining EV ownership over a 15-year vehicle lifetime shows that Vehicle-to-home charging can cut costs and greenhouse gas emissions across the USA. The study found that adding a battery-electric vehicle (BEV) increases the typical household electricity bill by about $6,300 over that period,⁹ but that is still significantly less than the cost of fuel for a regular gas vehicle.

When vehicle-to-home capability is added, the financial benefits expand. Research modeling V2H use across U.S. households suggests that using an EV battery to offset home electricity consumption, particularly during peak-rate periods or grid outages, can yield additional savings averaging about $3,800 over 15 years.¹⁰ These values do not take into consideration the potential savings from an outage (remember the last time you had an outage and had to throw away everything in the fridge and the freezer?)

In short:

• EVs cost less to fuel than gasoline vehicles
• EV charging increases household electricity use, but at a net savings
• V2H adds an additional layer of value by reducing grid electricity purchases
• Time of Use (TOU) also allows the consumer to “fill up” when rates are low and sell back when rates are high

And when paired with rooftop solar, V2H allows households to store excess daytime generation for later use, improving self-consumption and resilience.

Opportunities and Areas for Improvement

Think back to the size of PV modules years ago and how they have lately improved in wattage and footprint. What about how heavy lithium-ion energy storage systems used to be? Believe me when I say they were very heavy, and I hope my chiropractor doesn’t read this!

Vehicle-to-home capability is a promising technology, and several major automakers have now embraced it. This is good news for both consumers and the renewable energy industry.

When V2H is paired with rooftop solar, and optionally with stationary battery storage, homeowners gain more control over both their energy costs and their resilience during outages.

Bi-directional charging setup. © Baker Makarem

Additionally, as the technology becomes more common, there are several important opportunities for even more improvement.

Broader Access Across Vehicle Models

Today, V2H capability is more often limited to higher-priced, premium-trim EVs. Expanding this functionality across all EV segments, including mid-market models, would help ensure that energy resilience is not restricted only to higher-income buyers. Affordability remains a key factor in EV adoption, and widespread V2H deployment will depend on inclusive pricing strategies.

Enabling Flexible Self-Consumption

Another opportunity lies in enabling EV batteries to support household electricity needs during normal operation, not only during outages. For example, a home with rooftop solar could charge an EV during the day and then use that stored energy in the evening, when rates are higher, and the vehicle is available.

In a household with two EVs, where each car is only in use part of the time, a smart energy-management system could draw stored solar energy from whichever vehicle is available. This would:

• improve renewable-energy utilization
• reduce reliance on the grid during peak periods
• potentially lower the size and cost of stationary energy storage systems (ESS)

Open Standards and Interoperability

Today, some V2H systems are closely tied to proprietary home-energy ecosystems. For homeowners with a solar installation, retrofitting a brand-specific V2H product can add cost and complexity.

Allowing EVs and chargers from different manufacturers to communicate and interact at the bidirectional level would:

• allow V2H systems to integrate with existing PV installations
• reduce hardware compatibility barriers
• give consumers greater freedom of choice
• lower system costs over time

This approach treats the EV more like a universal “battery on wheels,” rather than a product locked inside a single ecosystem.

Real-World Example

Imagine a household with two EVs. A severe storm is forecast, and nearby family members, who already have rooftop solar, lack backup storage. With interoperable V2H systems, the homeowner could temporarily connect one vehicle to power the home during an extended outage and lend the second vehicle to the other home.

This type of clean, mobile backup could avoid the need for a fossil fuel generator or the cost of installing a stationary ESS with smaller capacity — potentially saving $10,000 or more in hardware and installation.

Giving consumers that flexibility allows the technology, as well as the market supporting it, to grow naturally.

Economic Factors Shaping the Future of V2H and EV Adoption

Economic policy plays a central role in how quickly new energy technologies are adopted. Recent federal tax credits for EV purchases in the U.S. helped accelerate market growth, but their expiration in 2025 may signal a new phase, one focused on affordability and cost reduction rather than incentive-driven demand.

In theory, tax credits can stimulate technology adoption, and with that, research into technology improvements. However, credits may also allow manufacturers to maintain higher pricing, as part of the purchase cost is absorbed by public support.

When incentives decline, market competition often shifts toward lowering production costs and expanding access. This dynamic may help explain why several major automakers are now refocusing on lower-cost EVs, hybrids, and plug-in hybrid models.

These U.S. EV manufacturers that provide V2H (Ford, Tesla, Kia, GM) did not start with lower-cost EVs from the beginning, as other countries did.

Another factor influencing EV pricing is the tariff structure applied to imported components and materials. As economist Thomas Sowell notes in Basic Economics, tariffs tend to raise the final cost of consumer goods by shielding domestic producers from lower-priced competition.

Ultimately, these costs are borne by end users, including EV buyers. As the industry matures, tariffs and trade policy will continue to affect affordability and, thereby, adoption speed.

If you cannot compete, then allow other manufacturers to provide their products and learn from them.

What the Next Phase May Look Like

In the near term, smaller, lower-cost EVs equipped with V2H capability may represent an important bridge technology. This model is particularly well-suited to urban areas where daily driving distances are modest, charging access is common, and electricity costs are above the national average, particularly in places that have Time of Use prices.

In these settings, pairing a compact EV with rooftop PV and maybe also a modest stationary ESS can deliver meaningful economic and resilience benefits.

Plug-in hybrid electric vehicles (PHEVs) may also play a role. With battery capacities now ranging from roughly 10 kWh to as high as 70 kWh in some new global models, PHEVs can offer both electric-driving capability and long-range flexibility.

If V2H functionality becomes standard across PHEV offerings, households in regions with limited charging infrastructure could still benefit from bidirectional energy use.

Bi-directional charging setup. © Baker Makarem

Incentives Beyond Federal Policy

Even as federal EV purchase credits phase out, state and utility-level incentives remain active across much of the country.

For example:

• Arizona Public Service offers programs such as EV Charging Assistant Rewards, which adjust charging schedules to align with renewable generation and grid needs, providing both sign-up and monthly participation credits.
• The Illinois Environmental Protection Agency continues to provide rebates for qualified buyers of new or used all-electric vehicles.
• Many utilities nationwide now offer off-peak charging rebates or TOU rate incentives, further lowering operating costs for EV owners.

These programs encourage smart-charging practices that align well with V2H, where vehicles are viewed not only as transportation assets but as flexible energy resources. This also allows utilities to study energy consumption for better forecasting of their power generation.

Looking Forward

As the EV and solar industries evolve, several questions will shape the next decade:

• Will V2H become a standard feature across vehicle classes?
• How quickly will open interoperability standards expand consumer choice?
• Will the combination of EVs, rooftop solar, and smart charging reshape how households think about energy independence?

What seems increasingly clear is that vehicle-to-home capability strengthens the connection between transportation and clean energy, turning the EV into a cornerstone of resilient, distributed power.

About the Authors
Baker Makarem is a Mechanical Engineer and NABCEP-certified ESIP, PVIP, and PVSI. He is the founder of Bakertech, a company specialized in the photovoltaic (PV) and energy storage systems (ESS) industry. He has been in the renewable energy field since 2017.

Carla Monzer previously worked as a marketing consultant in a global market research firm providing consumer, industry, and market intelligence. She is currently a PhD student in Marketing at the University of South Florida. Her research interests focus on sustainability, with particular attention to renewable energy and its interaction with
consumer behavior.

Sources:

1. tinyurl.com/global-ev-outlook
2. tinyurl.com/edmunds-2025
3. tinyurl.com/doi-ev-pv-nexus
4. tinyurl.com/eia-todayinenergy
5. tinyurl.com/afdc-emissions
6. tinyurl.com/car-and-driver-range
7. tinyurl.com/fred-APU000072610
8. tinyurl.com/fred-APU000074714
9. tinyurl.com/natures41560-025-01894-7
10. tinyurl.com/2025-big-three

Students at Huffman High School in Birmingham are building a solar-powered tiny home — a first-of-its-kind collaboration for the University of Alabama at Birmingham aimed at preparing teens for careers in construction and renewable energy. The tiny home will connect to the university’s Solar House microgrid.

The UAB Solar House itself began as a competition entry for the U.S. Department of Energy’s 2017 Solar Decathlon. Designed and constructed by Alabama college students to maximize energy efficiency in Alabama’s hot, humid climate without sacrificing comfort, livability, and style, the 1,000-square-foot home is powered by the sun.

After the competition, the house was moved back to UAB’s campus where it was “islanded,” meaning it was not tied to the city’s electrical grid. Instead, it houses its own remote microgrid for energy storage.

The partnership between UAB Sustainability and Huffman’s Academy of Architecture to build the tiny house is part of Phase 2 of the Solar House and Sustainable Community project, which received funding from EBSCO (“Elton Bryson Stephens, Company”) in 2019. The project’s goal is to expand the off-grid solar-powered community and to model resilient, self-sufficient, and regenerative communities for the Southeast.

According to Bambi Ingram, Chief Sustainability Officer at UAB and the lead for both this project and The UAB Solar House, “The UAB Solar House and Sustainable Community demonstrates the potential for resilient technology to reshape communities. By training high school and college students to do this work, we are empowering the next generation to create spaces that work for them.”

The UAB Solar House’s backyard. © The University of Alabama at Birmingham

Through the partnership with Huffman’s Academy of Architecture, the project is providing critically important workforce development opportunities in Birmingham, where more than 25% of residents live in poverty. Huffman High School is the largest school in the Birmingham City Schools system, and serves a 98% minority student body.1, 2 Huffman’s students are learning practical skills that will pave the way for future success in fields like construction, solar installation, and electrical engineering.

According to their construction teacher Jacques Dean, ”Because of our partnership with the UAB Solar House, our students are learning to plan, design and install residential solar. That’s a valuable skill set and will make them even more competitive for jobs in the construction industry.”

Students in the Academy of Architecture program choose one of three pathways: Design and Preconstruction, Construction, or Maintenance and Operations. The academy opens the pathways to steady careers in countless fields, including drafting design, welding, electrical technology, heating, HVACR, carpentry, cabinetmaking, masonry, plumbing, and pipefitting. The program is affiliated with the National Academy Foundation (NAF), a leader in the movement to prepare young people for college and career success.

Bambi Ingram, Chief Sustainability Officer at UAB, says: ”We are looking forward to welcoming even more visitors to our community so that we can share our experience of what does and does not work in creating and managing off-grid projects. It’s an exciting collaborative venture that has the potential to be of great service to the region.”

Since 2021, the house has served as the center of UAB Sustainability’s Solar House and Sustainable Community project. It has functioned as a living lab and center of environmental education for residents of and visitors to Central Alabama. Countless K-12 groups, college classes, and local community groups and nonprofits have toured and used the space to engage in educational opportunities related to solar power, renewable energy,
and sustainability.

The Solar House and Sustainable Community is located at 1637 11th Ave S and is open to the general public for educational tours.

The tiny home is expected to be completed by March 2026 and integrated into the community by year’s end.

About the Author
David Kirby is a passionate environmentalist and sophomore BSW student at The University of Alabama at Birmingham. David works for UAB Sustainability as the coordinator of the UAB Solar House, which has participated as a site for the annual ASES National Solar Tour since 2021.

In a Sahuaro Forest

We moved to this property, an old mining claim surrounded by Sahuaro National Park in Arizona, in 1988. The nearest neighbor and power were almost two miles away. We had been designing and building passive solar homes for some time, and this was our chance, finally, to live off the grid. It has been a wonderful experience, and we have learned many things, refined many concepts, and had great fun imagining ‘what ifs…’ Throughout those 35 years, we have witnessed knowledge, techniques, equipment, and systems steadily improve.

Our house was on the cover of Solar Today magazine, Sept/Oct 1996. We have come a long way since that time. It is beneficial to look at how things have changed and how to advance sustainable practices as time goes on.

Gale, Richard, and Mathew Marsland featured on the 1996 Sept/Oct cover of Solar Today magazine.

Why Do Off-Grid

At the time we built our home, there were many reasons to take on the challenge of designing and building an off-grid home. We:

• Believed in climate change and wanted to contribute in every way possible.
• Considered ourselves to be innovators, problem solvers, and liked high-tech modern stuff.
• Wanted to access the incredibly abundant solar resource where we lived.
• Believed in having a small footprint and finding more ways to do that
• Wanted to be independent from monopolies and institutions.
• Knew that life cycle costs could be less, over 30 years x $166/month = $60K.
• Wanted fewer neighbors and to be surrounded by the natural environment.
• Still hold these values as paramount.

Electricity Supply was the Initial Main Driver

Due to high costs and limits of technology in 1988, of utmost importance to us was to focus on reducing electricity needs as much as possible. Although strategies vary in different climates, some aspects remain the same and have similar solutions. We chose to operate several systems with propane: backup hot water heating, hot tub, dryer, and
space heating.

Energy Efficient Components

Building efficiency into the design of the home, we used the best available insulation for walls and roof, and high-quality windows and doors. We originally used the curliecue fluorescent bulbs, but now we have replaced them with LED bulbs, which use only 10% of the original incandescent bulbs’ wattage. When buying appliances, we chose the most energy-efficient available. The Energy Star website was very helpful. Originally, we used a propane refrigerator, then a super-efficient DC refrigerator that became available later. Now we use the readily available high-energy efficiency refrigerator
and appliances.

Passive Solar for Heating

In this sunny climate, we are able to do 90% of our heating with passive solar. We have a wood fireplace and a small propane heater for cloudy days. We can also use the mini-splits for backup heating. Passive solar components have not changed much and work to a degree in many climates.

The living room is the thermal mass and has south-facing windows. © Gale Marsland

Our house has large, true south-facing windows. They allow the sun in the entire width of the house in the winter and barely come in even a foot in the summer due to the sun’s high angle in the sky. Exterior shutters allow us to control the amount of sun coming in, which is particularly helpful in the spring and fall. They also limit heat loss at night in cool weather, with an added bonus of privacy and security enhancement.

The Marslands’ repurposed the cool tower into a wonderful observation deck. © Gale Marsland

My husband comes from a family of masons, so it was natural to use high mass concepts. The exterior walls and most interior walls are block, and the floors on the first floor are brick. All of this mass stores coolth/warmth and keeps temperatures from fluctuating quickly. The exterior walls are 20” thick with a split-face block on the outside, which blends in with the natural environment. There are 2 inches of isocyanurate foam plus a 2 inch air gap in between, completed by a solid grouted concrete block wall on the interior. We got the mass, the insulation, and a no-care exterior. About a third of the walls are buried underground 3-4 feet, which further provides insulation and contact with even more mass.

Tackling the Biggest Energy User – Cooling

Summer cooling was our biggest challenge. Because of low humidity, we were able to use evaporative cooling and didn’t require air conditioning. Bill Cunningham at the Environmental Research Lab in Tucson helped us address cooling while maximizing solar energy use. Part of our solution was a cooling tower originally developed a thousand years ago in the Middle East, known as a malquaf.

Bill designed a 35’ tall, 10’x10’ tower, with thick evaporative cooler pads on all four sides at the top. Water dribbled from the top down into a gutter and then recirculated. It only used about 50 watts to pump the water! The water coming through the tower cooled the air and, being heavier, dropped passively into the house. Cupolas on the roof vented warmer air out. This resulted in incredibly low power needed for cooling a 2000 square foot area. However, it used a lot of water, about 3-400 gallons a day. With a dry well, we had to haul water. The cool tower also sometimes leaked and stained the ceiling.

Later, we switched to a high-efficiency solar chill evaporative cooler, also designed by Bill, using about 100 watts and only 100 gallons a day, which was a big improvement. Recently, we installed even more efficient AC mini-splits after adding to our solar array and generating plenty of electricity. The mini-splits use about 1000-1500 watts and ZERO water. Our comfort level is greatly improved, and we can just set a thermostat and walk away.

The 2024 PV being mounted directly on the roof. © Gale Marsland

Future Forward: More Photovoltaic (PV)

Components of Active Solar/PV have advanced significantly and are much more efficient. PV modules produce more energy per foot, and therefore take up less space. And prices are much cheaper now, too! Our first solar panels were $25/watt; the ones we most recently purchased were only $0.40/watt! Inverters are also now more efficient. Our original inverters were modified sine wave, and back then, even a few of our electrical devices didn’t work well with that. Modern sine wave inverters are essentially like grid power now. They also put out a lot more power than the older ones: 1,500 W on the modified sine wave versus 12, on my newest one. The controllers and interfaces are smaller, more efficient, and cost less, though not as much cheaper as the extreme reduction of PV modules. We originally used passive trackers to keep the PV 90 degrees into the sun as it moved through the day to maximize output. Now, due to increased efficiency and decreased cost, our newest panels are stationary on our roof.

Another important advance over time is that there are more local businesses installing and maintaining solar systems. Larger national companies are marketing DIY systems and also offer tech support, including Wi-Fi connections that enable technicians to access your system and advise on installation and maintenance issues. When we upgraded, we took advantage of investment tax credits that, unfortunately, are ending on December 31, 2025. Some rebates and incentives will remain in some states and municipalities to help reduce costs, but you have to be in the right state.

Current Challenges

Climate change and extreme weather events are making the grid more vulnerable. Redundancy, duplication, diverse sources, and focus on DISTRIBUTED generation are critical. Our house has two parallel PV systems, and each is backed up by a generator. We also have a transfer switch so that if one system has problems, the other can provide power for it.

A 2017 upgrade included adding an automatic battery watering system. © Gale Marsland

Currently, the vast majority of homes with PV have no storage, back-up, or ability to use the power they are generating when the grid goes down! Most solar companies today are installing grid-tied systems with no batteries. Locally and anecdotally, there are very few companies that are interested in or even capable of installing battery backup systems. There is limited access to service, repair, maintain, or upgrade batteries. This is why so few people make this choice. The hope is that this market will grow and evolve so that it will be more like buying an appliance: bring it home, and plug it in. It is of vital importance to grow the infrastructure for installation, service, and maintenance for these full systems.

The solar community (researchers, tech developers, manufacturers, distributors, installers, community leaders, and organizations like ASES) needs to strengthen and build connections to take on some major portions of the grid in diversity and redundancy. We need to grow influence and power to compete with fossil fuel interests. A goal would be to promote distributed generation, where the individual has major benefits and solar growth is not just in the direction of corporations or utility companies.

Off-Grid Regret

We have only one regret about being off the grid. Seasonally, our power usage changes dramatically, as happens in many climates. Our latest system was designed around summer cooling needs. The other six months of the year, our needs are thirty percent less. So, IF my system fed back into the grid, we would be CONTRIBUTING. But the cost of bringing power up here- the last time I checked in 2018 – was over $60,000. It does not make sense to pay that plus a small monthly fee just to feed the grid. As I write this in October 2025 at 11 am, 17K of my 18K PV feed is already shut off, and batteries are at 100%. What a waste….so our best choice would be grid-tied with battery backup, and GET IT ALL: independence, clean energy, and contribution to the grid.

There are many sunny places, like Tucson, where you absolutely should invest in battery backup.

About the Author
In the 1980s, Gale Marsland designed passive solar homes and partnered with a PV installer in the mid-90s doing mostly off-grid. As time went on, she got more involved in the solar community and was a media spokesperson for ASES Buildings Division and on the Editorial Advisory Board for Solar Today magazine. In 2001, she drifted into planning, designing, and building sustainable communities.

Knowing the optimal location for installing a solar array increases annual generation by several percentage points if shade from nearby structures and trees is minimized, if not eliminated. Knowing how much energy is lost to shade helps homeowners decide whether to keep a tree or structure, trim it, or remove it. In general, it comes down to minimizing losses with nominal, if any, tree removal. In addition, by knowing the cost of leaving a tree in place (lost generation) homeowners or solar developers can make an informed decision regarding a tree’s potential removal.

Site Selection in the Sun

Sometimes, moving the solar array a little can make a big difference. For example, shifting the panels 20 feet to the east and 20 feet to the north might reduce shade from a barn by 85% and from a tree by about 10%. Moving the array further north can reduce shade even more.

It’s also important to consider the cost of lost energy. If a solar array produces about 8,400 kWh per year, a 5.7% loss due to shade could mean about $48 less in savings each year. Over 20 years, that adds up to nearly $1,000. If moving the array can save that money, it might be worth it.

The first step in estimating shade interference is to determine the solar declination angle (angle between the sun’s rays and the Earth’s equatorial plane), solar altitude angle (angle of the sun’s center above the horizontal plane), and azimuth angle (horizontal direction of the Sun) at regular time intervals for every day of the year. The solar altitude angle determines the length of a shadow while the azimuth angle determines the direction of the shadow. Geographic tools with these angles are readily available on the internet. Suncalc.org, for example, has map imagery and a calculator to visualize where shadows will be cast throughout the year. System designers use more powerful tools like Aurora and Helioscope to optimize siting.

The sun azimuth angle for incremental combinations of solar declination angle (day of the year) and solar altitude angle (time of day relative to solar noon) for any given latitude is calculated. The graph shows the maximum tree height (defined as the maximum height a tree can be without casting a shadow on the solar array at any time during the year) at a radius of 100’ from the solar array with assumed maximum generation losses of 0.5%, 1.0% and 1.5% (based on relatively low intensity of sun light in early morning and late afternoon hours); the given latitude is 38° N.

Maximum tree heights are determined by a small range of dates centered around the winter solstice for the azimuth angles ranging from approximately 132° to 228° with 180° representing due south which occurs at Solar Noon. As the azimuth angle moves lower from 132° or higher from 228° the controlling day for each respective azimuth angle moves from the winter solstice to the summer solstice. Tree heights controlled by the winter solstice reflect days where solar altitude angles are not large enough to clear a tree taller than these limits. This shading from trees and buildings when the sun is at low angles doesn’t actually impact total production very much because the sun is at such a great angle to the plane of the solar array that there would be very little energy generation at that time period even if the trees or buildings were absent. Maximum tree heights for azimuth angles not associated with the winter solstice are dictated by the shallow solar altitude angles that occur in the early morning and late afternoon periods of the day.

A simple way to interpret/use this chart is to assume generation losses will not be exceeded if the surrounding tree/structure profile for the entire range of azimuth angles is below its relevant height limit. Areas where trees/structures are less than the maximum would reduce this annual loss estimate. Perhaps it goes without saying but height limits are proportional to the distance from the solar array.

Estimating Shade Loss

The profile of any object can be defined by a series of combinations of azimuth angles and solar altitude angles. The potential for shading begins when the angle between the object and the western end of the array matches the azimuth angle. As the day wears on, the azimuth angle works its way west to east along the array. Shading ends when the angle between the object and the eastern end of the array matches the azimuth angle.

Trees located closer to due southwest and southeast have a much greater impact on potential generation losses. © Steve Moss

Within this range of azimuth angles, shading will only occur if the solar altitude angle is less than the vertical angle from the array to the top of the object (defined here as the minimum solar altitude angle). Although the minimum solar altitude angles within the range of azimuth angles can be easily calculated, the amount of the resulting lost generation is a much trickier value to calculate. This is because both the azimuth angle and solar altitude angle behave as a sine wave throughout the year. In addition, the intensity of sunlight is a function of the solar altitude angle; meaning the potential for generating electric power diminishes as the sun gets closer to the horizon.

Loss Due to Tree Shading

To determine the potential generation loss of a tree, the distance between the tree and the solar array and the azimuth angle are measured at site. The western end of the solar array is used for both measurements. The azimuth angle can be determined with the compass app on a smart phone by standing at the tree and pointing the phone toward the solar array. The tree height is also estimated (this can be done by someone holding a pole of a known length next to the tree and an observer visually estimating the tree height in terms of the number of pole lengths needed to match the tree’s height). There are, of course, more sophisticated methods of making these measurements.

The tree height, distance to tree, and azimuth angle are entered into a spreadsheet along with the dimensions of the solar array. Azimuth angles and distances to the tree are calculated for the various points along the object’s profiles. These distances are used to determine the minimum solar altitude angle for these various points.

Please refer to the plot sketch for a better understanding of a tree and barn location relative to the solar array. For illustration purposes, the tree’s profile is defined as two concentric cylinders; the first has a 6’ diameter and height equal to the estimated height of the tree; the second has a 12’ diameter and a height 5’ less than the height of the tree. These values can be varied and additional cylinders added, if needed.

In most cases, the shadow width will be less than the width of the solar array. Allowances are made for the fact that generation does still occur within the range of applicable azimuth angles.

In reality, the estimated width at the maximum tree height is an educated guess and will probably be less as the width dimension is taken closer to the top of the tree. In addition, no allowance for partial shading is made. It is also assumed the tree shadow is solid for the entire time it interferes with the solar array and does not factor in space between leaves, nor does it take into account the lack of leaves for non-evergreens during the winter months.

Loss Due to Structure Shade

In most cases, the dimensions of structures can be more accurately measured and shade losses more accurately estimated. Loss estimates are generated with the same method as for a tree.

Structure profiles are constant and not subject to seasonal variances; thus, fairly accurate loss estimates can be achieved and should be weighed accordingly when balancing between competing estimated losses associated with trees.

Optimizing Array Location

Site conditions may limit location flexibility, perhaps a range of trees to the immediate north of the proposed array location. There may also be limits based on aesthetic considerations. Perhaps, if the owner had no choice this could be acceptable, but if the owner could significantly reduce or even eliminate the loss by moving the array it should be considered. Although already well-established, the minimum distance between parallel arrays can also be calculated. This distance increases with latitude; variances in the topology of the area the arrays are being installed must also be considered.

Perhaps the most practical knowledge is the minimum distance required to avoid shading altogether. Another possibility may be determining if the array should be split into two (or more) rows if the site has competing shade producing or space limits to the east and west of the array. Alternatively, if there is a ridge of trees to the south of the array but not much to the east and west, a single solar array is likely the best configuration.

Trees and landscaping provide essential environmental benefits, but always consider how much shade they’ll throw as they mature. Deciduous trees (ones that drop leaves) on the east or west can block harsh summer sun while minimizing winter shading, but keep them far enough south from an array or rooftop system to prevent significant generation loss. Proper solar siting is essential for optimizing a solar array’s location and minimizing the impact to the nearby landscape—green is good!

Practical Tips for Homeowners

• Assess the site: Look at where trees and structures are located relative to the panels. Use a compass app on a smartphone to measure the direction from the tree to the panels.
• Estimate tree height: Hold a pole of known length next to the tree and estimate how many pole lengths it takes to match the tree’s height.
• Use tools and charts: There are online tools and charts that can help estimate how much shade a tree or structure will cast and how much energy might be lost.
• Consider alternatives: Sometimes, trimming branches or moving the array can reduce shade without removing trees. If removal is necessary, weigh the environmental benefits of solar energy against the loss of the tree.
• Consider Future Growth: Trees will grow, and new buildings may go up nearby. Factor this in—trim branches or plan for a little extra space.
• Advanced Panel Tech: If minor shade is unavoidable, panels with microinverters or power optimizers limit the “bottleneck” effect from a single shaded cell.

Example of a 50’ Tree

For illustration purposes a 50’ tall tree located 55’ east and 50’ south of the western end of the solar array is assumed. The range of affected azimuth angles is 130° to 164° for the 6’ diameter portion and 128° to 167° for the 12’ diameter portion. Minimum solar altitude angle ranges from 34° to 41° for the 6’ diameter portion and 31° to 38° for the 12’ diameter portion. The 12’ diameter minimum solar altitude angles are lower because the assumed height is 5’ lower than for the 6’ diameter portion.

This tree will provide an estimated 170 hours of shade and reduce annual generation by about 2.6%. General loss estimates for alternate locations will be discussed in the context of minimizing the total of this tree and a nearby barn later in this article. Note: the 170 hours represent about 3.9% of total hours of sunlight; the difference between this and the loss estimate reflects the lower intensity levels associated with some of the shaded area.

Example: A 20’ tall barn with its northern wall located 20’ south with its eastern wall located 20’ west of the western end of the solar array. All four sides are 40’ long. For simplicity, the orientation of this barn is assumed to be true to the N/E axis. With this barn’s assumed dimensions and location, the associated azimuth angle range is 198° to 257° with the minimum solar altitude angle ranging from 13° to 18°.

This barn would provide an estimated 240 hours of shade and reduce annual generation by about 3.1%. As was the case for the tree example, the estimated loss value is much less than the 5.5% of annual hours where this barn is shading the solar array due to the lower intensity of much of the area affected.

The combined annual generation loss of the tree and barn is about 5.7%. The typical capacity of a 25’-wide array is about 6 kw which would be expected to produce about 8400 kwh’s per year. Applying this loss estimate to the total generation yields annual cost estimates of about $48 based on a value of $0.10 per kwh. Assuming the discount rate equals the inflation rate of electricity, the NPV of this annual cost comes to about $960 based on a 20-year life of the array.

If the array can be moved 20’ to the east and 20’ to the north, estimated generating losses of the barn are reduced about 85% to 0.5% annually while losses tied to the tree are reduced more modestly by about 10% to 2.3%. The losses tied to the tree are reduced by the array shift north but this is almost entirely neutralized by the move east.

Starting at this secondary location and moving the array north by another 20’, losses to the barn and the tree are each reduced to about 0.2%. At this point, the benefit of moving further north may need to be compared to any additional cost or detriment that may be incurred.

About the Authors
Steve Moss received a BS in Mechanical Engineering from the University of Missouri – Rolla (now MS&T) in 1976 and retired from Nooter/Eriksen as a Senior VP in 2015 after 39 years of service. Mr. Moss is a past president of the Academy of Mechanical and Aerospace Engineers at MS&T and is currently a trustee at Ranken Technical College, located in
St. Louis, MO.

Carly Rixham is the Executive Director for American Solar Energy Society (ASES). She is the Publisher of Solar Today magazine. Her research is in the intersection of solar energy and landscape architecture. She received her Masters in Ecology and Evolutionary Biology at University of Colorado Boulder. Rixham was a microbiologist at BioVantage Resources, culturing algae for bio-remediation of nutrients in wastewater. She enjoys travel, art, mountain sports, and nature.

The solution lies not in inventing new equipment but in reimagining how capital flows. From my experience in energy finance, I’ve seen that access to clean energy follows the same logic as access to credit: it rewards those who already have assets and excludes those who don’t.

A more balanced approach – what could be called blended finance creates shared ownership by aligning government support, private investment, and community participation. It’s not just a funding mechanism; it’s a philosophy of collaboration.

The Limits of Traditional Solar Finance

Traditional project financing favors scale, predictability, and low risk. Those parameters are ideal for utilities and corporations but leave behind rural cooperatives, low-income neighborhoods, and tribal nations.

The barriers are structural: limited collateral, lower consumption levels, and fragmented demand. Yet these same communities stand to gain the most from solar energy with lower bills, local job creation, and energy resilience.

Blended Finance: A Framework for Shared Benefit

Blended finance works by combining three sources of capital that, together, create stability and trust in a project:

• Public capital provides seed funding, often in the form of grants or guarantees, reducing risk for others.
• Private investment supplies most of the funds, motivated by steady returns and clear cash flows.
• Community participation through cooperatives, bonds, or local subscriptions ensures affordability and ownership.

When these forces align, the outcome is a self-reinforcing model: government funds attract private capital, which in turn multiplies community participation. It’s a virtuous cycle that transforms solar projects from external interventions into locally sustained enterprises.

From Concept to Impact

Imagine a solar project serving hundreds of households. Instead of asking who will pay first, the model asks: how can each actor benefit proportionally? The government sets the foundation, private investors bring efficiency and discipline, and communities provide purpose and stability. Together, they form an ecosystem of shared power. The results can be transformative.

Households gain predictable energy costs. Investors secure long-term revenue streams with low volatility. Local organizations from schools to cooperatives gain recurring income through participation fees or ownership shares.

Every dollar invested in generates electricity and increases social and economic value.According to the National Renewable Energy Laboratory (NREL), distributed solar can generate up to 15 local jobs per million dollars invested. Add community participation and those jobs turn into careers sustained by pride, not subsidy.

Lessons from the Field

In several pilot experiences I’ve observed, community-driven financing has changed the tone of renewable projects entirely.

Instead of external developers promising benefits, residents become co-owners of progress. When communities invest modestly, they protect the project, attract talent, and spark a sense of belonging.

The Department of Energy’s Community Power Accelerator shows that partnerships between public agencies and local cooperatives can reduce costs by 15–25% compared to purely private development. Financial innovation, not just engineering, is what unlocks that potential.

Data-Driven Design and Replication

Equitable solar finance needs data and transparency. Projects should start with a financial model that measures social impact and ROI. Tools like Power BI dashboards and open-source models help stakeholders preview project outcomes before installation.

A practical example is creating a revolving fund that automatically reinvests part of community savings into future installations. This mechanism ensures scalability without dependence on continuous government subsidies.

A Call for Collaborative Policy

To scale inclusive solar financing, policymakers must think beyond tax credits. The key is to blend grants with soft loans, standardize community participation models, and simplify permitting for shared ownership.

Programs like the Rural Energy for America Program and state-level clean energy banks are already testing these ideas but coordination remains essential. Financial innovation should be treated as a clean-energy technology subject to research, testing, and replication. By fostering open dialogue between financiers, engineers, and communities, we can ensure that no one is left behind in the solar transition.

The Power We Share

The energy transition will not be won solely by megawatts or tax credits; it will be won by inclusion. Shared power means more than electricity generation; it means shared responsibility and shared prosperity. Blended finance is not charity, it’s strategy. It creates projects that make financial sense while building social capital. The future of solar finance lies in collaboration.

By aligning incentives, empowering communities, and trusting in the multiplier effect of shared ownership, we can turn sunlight into opportunity for all.

About the Author
Christian Custode is a financial strategist and ASES member specializing in renewable energy investment models. He serves as Financial Planning & Portfolio Economist at Ecopetrol USA, Inc and leads Business Planning Consulting LLC, focused on sustainable finance for community solar and tribal energy projects.

This year’s Tour brought together over 800 solar and sustainable sites across the country, from solar-powered homes and schools to large-scale community and agrivoltaic projects, each one inspiring visitors to take steps toward clean energy adoption in their own communities.

Thanks to all the hosts, volunteers, and visitors who made this milestone year so impactful! Your enthusiasm and commitment to renewable energy are what make the Tour the nation’s largest grassroots solar event.

We’ve received inspiring stories and photos from Tour participants nationwide, showing how local action continues to drive the clean energy transition. Together, we’re proving that solar works everywhere, for everyone. View the solar tour map at map.nationalsolartour.org.

2025 National Solar Tour Highlights

How to Attend In-Person Tours: Although the showcase weekend is over, there are still in-person tours taking place all throughout the rest of the year! Check out the National Solar Tour map or digital app to RSVP to in-person tours near you to view the exact address. Optionally, some hosts have made their street address, email address, or phone number viewable in the tour description as well.

How to Attend Virtual Tours: View all the virtual tours featured on this year’s National Solar Tour, simply head to our National Solar Tour map and start selecting the pins you’re interested in, or use the filter feature on the top left hand corner of the map. These virtual tours contain various photo and video tours featuring a wide range of sustainable features.

© Ben Zook

Ben Zook’s Solar Home: Ben Zook, owner and NABCEP Certified Master Electrician at Belmont Solar, hosted a passive solar open house on October 4, featuring a 33 kW solar PV system with 40 kWh of onsite storage, enabling off-grid operation. Upgrades to insulation, windows, and skylights improved comfort while maintaining the home’s original design. Powered entirely by renewable energy with no fossil fuels or gas connections, the home included EV charging, a ground-source heat pump, and all-electric appliances such as an induction cooktop and heat pump systems. With exceptional indoor air quality and abundant natural light, the home operated beyond net-zero.

© Brett Little

Little Residence GreenStar: Join Brett Little, Education Manager at the GreenHome Institute, who wants to invite you over to his home (virtually) as part of the American Solar Energy Society National Solar Tour! Discover how he transformed a 2002-built residence into an all-electric, solar-powered home, achieving a DOE Home Energy Score of 10, PEARL Platinum Certification, and the ultimate holistic approach using the GreenStar Homes Certification. This tour will guide you through the process of transforming a traditional home into a sustainable showcase, covering every step from initial green inspections to upgrading heating, cooling, ventilation, appliances, plumbing, and more—all while maximizing comfort, safety, and utility cost savings.

Utility-Scale Oxbow Solar Project: The Oxbow Solar project is a utility-scale solar farm generating 345 MW-dc / 300 MW-ac of clean, locally produced electricity. Its construction created 400 jobs, the majority filled by local workers, and represents a $394 million private investment in Louisiana’s energy infrastructure—strengthening the state’s energy security. Each year, the project reduces approximately 458,000 metric tons of CO₂ emissions, equivalent to removing about 100,000 fuel-burning cars from the road. Over the next 35 years, it is projected to provide $30 million in revenue to Pointe Coupee Parish government agencies.

© Exact Solar

Exact Solar Local Tour: At Exact Solar’s Local Tour, visitors can explore more than twenty virtual tours showcasing solar installations from their own customers. Each tour highlights unique solar projects from residential rooftops to local businesses, demonstrating the real-world impact of clean energy adoption. These videos showcase firsthand stories from homeowners and business owners about their experiences going solar, including the motivations behind their decisions, the benefits they’ve seen in energy savings and sustainability, and how solar has helped strengthen their communities.

About the Author
In the 1980s, Gale Marsland designed passive solar homes and partnered with a PV installer in the mid-90s doing mostly off-grid. As time went on, she got more involved in the solar community and was a media spokesperson for ASES Buildings Division and on the Editorial Advisory Board for Solar Today magazine. In 2001, she drifted into planning, designing, and building sustainable communities.